1. Field of the Invention
The present invention relates to a glass run channel assembly mounted to a door frame of a vehicle.
2. Description of the Related Art
Generally, a door frame (also referred to as a sash) provided in a main body of a door panel of a slide door, a front door, a rear door, or the like in a vehicle, such as a car, is mounted with a glass run channel assembly (referred to as a glass run, a glass run channel, a guide member, etc.). The glass run channel assembly for this application is a groove forming member (long molding member) which is molded long and has a substantially U-shape cross-section, and is mounted to a groove formed in a door frame, thereby guiding lifting of a windowpane which moves up and down inside a door. Generally, the glass run channel assembly is manufactured by performing extrusion molding or the like by using an elastic polymeric material, such as rubber or thermoplastic elastomer. For example, JP-A-2000-280749 describes a glass run channel which is formed in whole from a rubber material composed mainly of EPDM (ethylene propylene diene rubber) or TPE (thermoplastic elastomer).
Generally, in a glass run channel which is extrusion-molded using an extrusion molding material including a rubber material like EPDM, the specific gravity of the rubber that is a molding material is about 1.1 to 1.3. This molding material has a drawback that the weight per unit volume becomes larger than a glass run channel manufactured in the same shape by a soft olefin system thermoplastic elastomer (TPO) whose specific gravity is about 0.9 to 1.0.
Meanwhile, the glass run channel made of TPO with advantage of lightweight has the following drawbacks.
(1) The soft olefin system thermoplastic elastomer has larger creep deformation than a soft rubber material. For this reason, when being mounted to the door frame and provided for use, the force of friction against the door frame becomes smaller than that of a glass run channel made of a rubber material if predetermined time (typically, 60 minutes) has lapsed. As a result, the channel deviates in position from the door frame. Although this positional deviation can occur regardless of the front door and rear door of a car, the positional deviation is apt to occur particularly in an inclination frame portion of an upper frame (which refers to an upper frame portion which is formed integrally with an upper end of a vertical frame arranged in a vertical direction along a center pillar of a car, and includes an inclination frame extending along a front pillar or a rear pillar obliquely downward from this upper end (the same hereinbelow)) of a door frame.
(2) The soft olefin thermoplastic elastomer has a larger static friction coefficient against a door frame than, for example, a vulcanized soft rubber. For this reason, resistance at the time of mounting operation to the door frame, specifically, at the time of insertion operation into the groove of the door frame becomes large, and mounting workability becomes inferior. Particularly, when the glass run channel is inserted into the groove of the upper frame of the door frame, an operator has to apply a pressing force upward from below, and from the viewpoint of ergonomics, this operation manner requires an excessive force, and gives excessive burden and fatigue to the operator.